"Game over" for climate change. So opines NASA climatologist Jim Hansen when it comes to the development of the Canadian tar sands. And one big way to unleash the estimated 170 billion barrels of heavy oil stuck in Alberta's sands is to build a pipeline to the world's biggest oil consumer: the U.S.

A new analysis by scientists at the University of Victoria in British Columbia suggests burning all those proven reserves would release enough CO2 to warm the climate by only one 20th of a degree Celsius. Global warming to date is 15 times that.

Nevertheless, building the pipeline keeps us in the carbon habit, through which the U.S. burns roughly 20 million barrels of oil a day along with copious quantities of coal and natural gas. Ending our fossil fuel addiction is the only way to truly combat climate change.